[AusNOG] EdgeRouter IPv6 on AussieBB

Karl Auer kauer at biplane.com.au
Sun Sep 8 15:43:33 EST 2019

On Sun, 2019-09-08 at 14:12 +1000, Alex Wakefield wrote:
> My internal interface manages to get IPs out of the range handed out
> by Aussie but clients never get an address after that. I'm trying to
> use SLAAC to hand out IPs. Relevant config on my internet facing port
> below.

I don't speak EdgeRouter but that secoond-last stanza looks to me as if
you are asking the interface itself to autoconf its own address. That's
probably wrong; IIRC a routing interface can't be autoconfed. Odd that
the router didn't complain if so, however.

Not sure if that prefix_length refers to what you get from the
upstream, or the prefix you are trying to advertise. If the latter, be
aware that nothing will do SLAAC on a prefix length other than 64.

If clients don't SLAAC themselves IPv6 addresses, it's almost always
because they are not configured to use IPv6 at all, or they are not
seeing RAs from the router. Easy to check by sniffing the link on that
interface - you should be seeing various kinds of IPv6 multicast
including RA.

Check that a test client definitely has a link local address; if it
does, it's doing IPv6. Then check that it doesn't have some kind of
"kill all ipv6" filter. You'd be amazed how often that's the issue -
someone turned off or blocked IPv6 to fix some problem they thought
IPv6 was causing. Some operating systems (like Linux at least) have a
"don't do SLAAC" switch and/or an "ignore RAs" switch.

Are those "firewall" stanzas definitely not blocking IPv6?

Try putting an IPv6 prefix on the link directly (no PD) and seeing if
the clients do their thing then. At least that will definitely exclude
client-side issues.

Regards, K.

Karl Auer (kauer at biplane.com.au)

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